This is an example using cell A1:
1. set the background color of cell A1
2. enter the following macro in a standard module:
Public oldcolor As Integer
Public lockcell As Range
Sub remember()
If lockcell Is Nothing Then
Set lockcell = Range("A1")
oldcolor = lockcell.Interior.ColorIndex
End If
End Sub
3. Enter this event macro in the worksheet code area:
Private Sub Worksheet_Change(ByVal Target As Range)
If lockcell Is Nothing Then Exit Sub
If Intersect(lockcell, Target) Is Nothing Then Exit Sub
lockcell.Interior.ColorIndex = oldcolor
End Sub
4. run the remember macro